Friday 22 October 2004 20.02 EDT
First published on Friday 22 October 2004 20.02 EDT

The Command of the Ocean: A Naval History of Britain Vol II 1649-1815by NAM Rodger 907pp, Allen Lane, £30

The British Seaborne Empireby Jeremy Black 420pp, Yale, £25

When we can eat Australian blueberries in the depths of winter, courtesy of air cargo, ships may seem redundant to some except for pleasure, their history an irrelevance. But we will always be an island, and 90 per cent of all our trade still comes and goes across the almost three-quarters of the Earth's surface that consists of salt water. This is a compelling reason for the study of naval history, as long as it has been written not to glorify the past, but simply to explain a great deal of it and its consequences.

Long the preserve of imperial historians such as William Laird Clowes and Julian S Corbett, a change in attitude to the subject can be detected from the moment the Society for Nautical Research was founded in 1910, with its dispassionately international approach. Ever since, through many long and increasingly unfashionable decades, British naval history has been in the hands of more detached (if not totally disinterested) scholars, of whom NAM Rodger is now by far the most exciting and original. The first part of his monumental naval history appeared in 1997 and a publisher's blurb has never been more amply justified: here at last is the "long-awaited" second volume.

Its predecessor began with the Dark Ages and finished with the execution of Charles I, and now Rodger takes the story on to the end of Napoleon's time, 10 years after Trafalgar. His approach is the same as before, based upon his conviction that our naval history has been "a national endeavour, involving many, and in some ways all, aspects of government and society", presented by him as such and not simply as an account of warfare at sea and the Royal Navy's preparations for it. Almost half of The Command of the Ocean , in fact, consists of background to events involving British men o'war, so as to place these in the widest possible context. Rodger thus dwells at length on the inherent problems of naval victualling, not simply to point out that the navy was the biggest purchaser of foodstuffs in the 18th-century London markets, but to demonstrate that its requirements actually encouraged and led to a commercial and agricultural revolution, "which made the British economy the most sophisticated in the world".

As before, his scholarship is formidably eclectic, typified by a table of sea battles and the various names by which they were known in different countries, which is "offered as a modest contribution to the reduction of confusion". It helps that he can evidently read the sources in several languages, which has enabled him to explore the intricacies of Dutch politics to explain the Anglo-Dutch wars of the 17th century. Here is that rarest of all historians, the expert with the generalist's approach to his speciality, though his academic instinct is sharp enough for him to criticise colleagues who in his view have got things seriously wrong.

There is wit here, as well as illumination. It's recalled that Sir Cloudesley Shovell, the much-loved admiral who was lost when three of his ships foundered on the Scilly Isles in 1707, had once said: "There is no storm as bad as one from the House of Commons." One of the themes running through the book is the constant tension between the politicians and the sailors, never greater than after the glorious revolution of 1689, when Parliament was packed with congenital landlubbers whose constant sniping reduced naval morale so much that some officers subsequently lost their nerve under fire. Rodger comes very close to claiming later that the American colonies were lost because the navy was not used more sensibly by the politicians in the events leading up to 1776.

Anyone with a military background or sympathies viewed the navy with suspicion, and it was eventually true that in popular esteem the sailors became "an expression of the liberty of the people, where the army was an expression of the power of the crown".

Yet it was the fleet that had brought Charles II home from exile in triumph - having first carefully replaced all its republican emblems with the royal insignia in mid-Channel - and it was Charles II who reinvigorated a navy that had first prospered and then declined during the Commonwealth, when one ship's company went without pay for four years. Far from being the lazy cynic of popular reputation, Charles attended meetings of the Navy Board more regularly than any official and he had a passion for the sea, which he enjoyed as the first patron of yacht-racing. He and his brother James II, in Rodger's view, understood naval technicalities better than any other sovereign "before or since". George III's knowledge was probably limited to what he learned from his son William, who was put into the navy in 1779, after which "his vast repertoire of dirty stories made him the terror of every genteel drawing room".

Other characters in an enormous cast are neatly sketched: the Dutch admiral Cornelis Tromp, a brave but nasty piece of work who tried to have his mild-mannered superior De Ruyter murdered; Samuel Pepys, linch-pin of the Navy Board, who profoundly disliked the gentlemen officers then being challenged by the "tarpaulins", the men with less breeding but much more maritime know-how; Lord St Vincent, the martinet who was on his quarter-deck before dawn each day to check up on the captains in his squadron who did not turn-to at first light; vice-admiral Collingwood, who burst into tears when his ship was decommissioned, which meant dispersing his crew; William Bligh and Fletcher Christian, the one an outstanding seaman with a bad temper, the other "a weak and unstable young man who could not stand being shouted at".

Horatio Nelson gets his due, as a commander who succeeded brilliantly because he secured the affection of his men, even though he was not by any means the greatest seaman around. Rodger summarises the gunnery at Trafalgar in some detail but, because he does not deal in clichés, we are spared yet another account of the death scene aboard Victory. Instead, it is pointed out that women sailed in English men o'war of the period quite frequently, and that a child was born aboard HMS Goliath during the Battle of the Nile.

Rodger does not cut corners either, so this is his second long book, made more so by a wealth of highly instructive appendices. He gives us interrelated naval, political, social, administrative, diplomatic, economic and religious history of a very high order, and anyone who reads it will hope we don't have to wait another seven years for the completion of the trilogy.

Jeremy Black has also approached his subject with wide terms of reference, his basic premise being that "Sea power made the empire what it was: without sea power there would have been no empire... in the form it actually took." This may seem self-evident to some, but as Black, too, occupies a chair in history, he is doubtless more aware of widespread ignorance than those of us of who were the last children of the British empire. He logs both the acquisition and the decline, noting the effect of both on the rulers and the ruled, and there are many intriguing glimpses of the evolution of the Pax Britannica (it was in 1831, for instance, that atlases first began to show British possessions in red, though foreign cartographers preferred different colour schemes). The naval element is carefully tracked, but this is essentially one for those who are puzzled by the concept or nostalgic for the experience of empire.

· Geoffrey Moorhouse's book on Henry VIII's navy will be published by Weidenfeld next year.